I've recently moved to protocol buffers and am quite happy with the results. Before that, we had a few tomcat apps with ad-hoc urls that return xml responses. S

I've recently moved to protocol buffers and am quite happy with the results. Before that, we had a few tomcat apps with ad-hoc urls that return xml responses. Since we already have a good http request/response channel, I was able to create a java bridge for the message objects, as well as a simple python library that can communicate with all our servers. While there was a little overhead in getting it integrated into the build system, it works great, and gives a much better interface, and much better control for messaging individual servers. The project itself is also very well put together. Hell, even the autoconf generated makefile has targets like "uninstall", which seems to be a rarity when building packages from source.